WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/394
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Article Citation - WoS: 3Citation - Scopus: 4On the Utility of Crystal Plasticity Modeling to Uncover the Individual Roles of Microdeformation Mechanisms on the Work Hardening Response of Fe-23Mn TWIP Steel in the Presence of Hydrogen(ASME, 2018-02-08) Bal, B.; Koyama, M.; Canadinc, D.; Gerstein, G.; Maier, H. J.; Tsuzaki, K.This paper presents a combined experimental and theoretical analysis focusing on the individual roles of microdeformation mechanisms that are simultaneously active during the deformation of twinning-induced plasticity (TWIP) steels in the presence of hydrogen. Deformation responses of hydrogen-free and hydrogen-charged TWIP steels were examined with the aid of thorough electron microscopy. Specifically, hydrogen charging promoted twinning over slip-twin interactions and reduced ductility. Based on the experimental findings, a mechanism-based microscale fracture model was proposed, and incorporated into a visco-plastic self-consistent (VPSC) model to account for the stress-strain response in the presence of hydrogen. In addition, slip-twin and slip-grain boundary interactions in TWIP steels were also incorporated into VPSC, in order to capture the deformation response of the material in the presence of hydrogen. The simulation results not only verify the success of the proposed hydrogen embrittlement (HE) mechanism for TWIP steels, but also open a venue for the utility of these superior materials in the presence of hydrogen.Article Citation - WoS: 4Citation - Scopus: 4Investigations of Electrical Resistivity and Thermal Conductivity Dependences on Growth Rate in the Al-Cu Eutectic Alloy(Springer/plenum Publishers, 2021-05-03) Marasli, Necmettin; Bayram, UmitDirectional solidification of Al-Cu-Ti (Al-33wt%Cu-0.1wt%Ti) eutectic alloy was done with a growth rate range (V = 8.58 to 2038.65 mu m.s(-1)) at a temperature gradient of 6.45 K.mm(-1) using Bridgman-type directional solidification furnace. The measurements of thermal conductivity (K) and electrical resistivity (rho) for the Al-Cu-Ti alloy solidified with the different values of V were made by the longitudinal heat flow method (LHFM) and DC four-point probe technique (FPPT). While the highest values of K and rho were determined to be 236.04 W.K-1.m(-1) and 5.91 x 10(-8) omega m, respectively, at 8.58 mu m.s(-1), the lowest values of K and rho were obtained to be 199.82 W.K-1.m(-1) and 12.11 x 10(-8) omega m, respectively, at 2038.65 mu m.s(-1). The K and rho dependences on V were obtained to be K=259.96xV(-0.032) and rho=4.47x10(-8)V(0.13) from linear regression analysis. The fusion enthalpy ( increment H) and specific heat difference between solid and liquid ( increment C-P) for the Al-Cu-Ti were also determined to be 222.69 J.g(-1) and 0.266 Jg(-1).K-1, respectively, by means of differential scanning calorimetry (DSC).Article Citation - WoS: 2Citation - Scopus: 3Investigation of Hydrogen Diffusion Profile of Different Metallic Materials for a Better Understanding of Hydrogen Embrittlement(Gazi Univ, 2023-12-01) Kapci, Mehmet Fazil; Bal, BurakIn this study, hydrogen diffusion profiles of different metallic materials were investigated. To model hydrogen diffusion, 1D and 2D mass diffusion models were prepared in MATLAB. Iron, nickel and titanium were selected as a material of choice to represent body-centered cubic, facecentered cubic, and hexagonal closed paced crystal structures, respectively. In addition, hydrogen back diffusion profiles were also modeled after certain baking times. Current results reveal that hydrogen diffusion depth depends on the microstructure, energy barrier model, temperature, and charging time. In addition, baking can help for back diffusion of hydrogen and can be utilized as hydrogen embrittlement prevention method. Since hydrogen diffusion is very crucial step to understand and evaluate hydrogen embrittlement, current set of results constitutes an important guideline for hydrogen diffusion calculations and ideal baking time for hydrogen back diffusion for different materials. Furthermore, these results can be used to evaluate hydrogen content inside the material over expensive and hard to find experimental facilities such as, thermal desorption spectroscopy.